JPH08127310A - Air bag control device - Google Patents

Abstract

PURPOSE: To prevent actuation caused by the offset voltage of an acceleration sensor by not making the start judgment of an inflator when the first speed change value reaches the threshold after the time after the first speed change value becoming positive exceeds the specified time. CONSTITUTION: When the first speed change value V1 does not reach the threshold TH4 even after operation carried out for the fixed time or more in order to avoid action caused by the offset voltage of an acceleration sensor, it is so judged that deceleration is not caused by a collision, and judgment operation is reset. With this action (steps 162-164), when the first speed change value V1 reaches the threshold TH4 after the time after the first speed change value V1 becoming positive, that is, the output elapsed time (t), exceeds the specified threshold 120ms, it is so considered that deceleration is caused by the offset voltage of the acceleration sensor, and the first speed change value V1, the second speed change value V2 and the operation elapsed time (t) are all cleared without making an actuation judgment so as to prevent the actuation of a device caused by the offset voltage of the acceleration sensor (steps 166-172).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an airbag control device for protecting an occupant from a collision, which device is activated at a good timing. In particular, the present invention relates to a device that does not operate due to offset voltage deviation of the acceleration sensor.

[0002]

2. Description of the Related Art Conventionally, the operation timing of an air bag system is set when a speed change value obtained by integrating a deviation of a deceleration of a vehicle at the time of a collision with respect to a predetermined threshold value is a predetermined value or more. In this case, since the speed change value may become the predetermined value or more even at low speed (about 15 km / h), a method of avoiding the operation of the airbag device in a low speed collision that does not require activation of the airbag. As Japanese Patent Laid-Open No. 4-
As disclosed in Japanese Patent No. 133840, etc., there is known a method of avoiding the operation at low speed by increasing the threshold value of the integral calculation of the vehicle deceleration.

[0003]

However, although the above method can distinguish a low-speed collision and a medium-speed collision, when deceleration occurs due to a factor other than the collision, for example, the acceleration sensor detects 1 g (g is an acceleration). In terms of the deceleration unit, when 1 g causes an offset voltage deviation of about 9.8 m / s ² ), the deceleration does not actually occur, but the deceleration of 1 g is electrically reduced. Since it has been detected, the speed change value may eventually reach the threshold value and the airbag device may be activated. Therefore, additional circuitry is required.

Therefore, an object of the present invention is to provide an airbag device which does not operate due to offset voltage deviation of the acceleration sensor.

[0005]

In order to solve the above problems, the structure of the present invention detects a deceleration of a vehicle by an acceleration sensor and integrates the deceleration and a predetermined speed change value set in advance. In the airbag control device that compares the threshold value and starts the inflator that ejects gas when the speed change value reaches a predetermined threshold value and inflates the airbag with the gas from the inflator, the first standard of deceleration. A first speed change value calculating means for calculating a first speed change value which is a time integration of a deviation with respect to a value, and a second speed change value which is a time integration of a deviation with respect to a second reference value larger than the first reference value A second speed change value calculating means and a starting means for starting the inflator when the second speed change value reaches a threshold value, and the time from when the first speed change value becomes positive is a predetermined time. Super Te, when the first speed change value has reached the threshold, characterized in that it does not perform the activation determination of the inflator.

[0006]

The first effect is that the time after the positive value of the first speed change value, which is the time integration of the deviation of the vehicle deceleration from the first reference value, exceeds a predetermined time, and the first speed change When the value reaches a predetermined threshold value, the activation of the inflator is not determined, and the first speed change value, the second speed change value, and the time after the first speed change value becomes positive are reset. (Claim 1)

[0007]

The first effect is that the offset of the acceleration sensor is set when the first speed change value reaches a predetermined threshold value after the time after the first speed change value becomes positive exceeds a predetermined time. It is considered that the deceleration is detected by the voltage deviation, and the first speed change value,
By resetting the time after the second speed change value and the first speed change value become positive, it is possible to avoid the operation of the airbag device due to the offset voltage shift of the acceleration sensor. (Claim 1)

[0008]

EXAMPLES The present invention will be described below based on specific examples. FIG. 1 is a schematic diagram showing the configuration of this embodiment. The airbag control device 9 inputs the acceleration signal detected by the acceleration sensor 15 and executes a collision determination calculation. When a collision is determined, a signal for activating the inflator is sent to the ignition device 4 of the inflator, respectively. It outputs to the transistor 31 connected in series. When this transistor is turned on, the ignition device 4 is energized and the inflator is activated.

Next, details of the controller 9 are shown in FIG. The control device 9 includes a CPU 91, a ROM 92 storing a control program and a collision determination program, an externally writable EEPROM 93, and a RAM 9 storing various data.
4 and A / D converter 95 and IF (interface) 9
6 and 6. RAM94 has an acceleration sensor 1
A threshold value memory area 941 for storing a threshold value for determining activation of the inflator corresponding to the physical displacement amount of the vehicle based on the deceleration signal from 5 is formed. The deceleration signal from the acceleration sensor 15 is input to the CPU 91 via the IF 96 and the A / D converter 95.

3 to 5 are main flow charts showing the processing procedure of the CPU 91 in the control device 9. First, at step 100 in FIG. 3, 1 (ms) is set for the elapsed time t of calculation.
Step 1
At 02, the deceleration G of the vehicle is read from the acceleration sensor 15. Here, the direction of acceleration applied to the vehicle is negative and the direction of deceleration G is positive.

Next, at step 104, the vehicle deceleration G is set to -2 in order to prevent the airbag from operating in the event of a rear collision of the occupant.
(G) It is determined whether it is smaller than. In FIG. 3, when the vehicle deceleration G is smaller than −2 (g), YES is determined in step 104 and 2 g is determined in step 106.
Add 2 to the counter, then 2g in step 108
It is determined whether the counter is 15 or more.

When the 2g counter is 15 or more,
It is determined to be YES in step 108, then the 2g flag is set to 1 in step 110, and 2g in step 118
When it is determined whether or not the flag is 1, it is determined to be YES, and in the following step 120, the first speed change value V1, the second speed change value V2, and the operation elapsed time t are all set to zero, and the process returns in step 122. . When the 2g counter is smaller than 15, it is determined to be NO in step 108,
In step 118, it is determined as NO in the determination of the 2g flag, and the process proceeds to the integral calculation of step 124.

In step 104, the vehicle deceleration G is -2.
In the case of (g) or more, it is determined as NO and the following step 1
At 12, the 1 is subtracted from the 2g counter. If the value of the 2g counter is greater than or equal to zero, N is returned in step 114.
When it is determined to be O, the process proceeds to step 118. When the value of the 2g counter is smaller than zero, YES is determined in step 114, the 2g counter is set to zero in step 116, and the 2g flag is set to zero, and the process proceeds to step 118.

In the processing from step 104 to step 118 shown above, when the 2g counter becomes 15 or more, the first speed change value V1, the second speed change value V2, and the calculation elapsed time t are all cleared. , -2 (g) and the deceleration smaller than -2 (g) continues for 7.5 ms or more, it is considered that the vehicle is not in a collision and the inflator is not started.

Subsequently, when it is determined at step 118 that the 2g flag is not 1, the routine proceeds to step 124, where the integral calculation of the deceleration G is performed. First speed change value V1
Is the integral of the deviation of the vehicle deceleration G from the threshold value 1 (g), and the second speed change value V2 is the threshold value α of the vehicle deceleration G.
It is the integral of the deviation from (g). Where the threshold α
(G) is larger than 1 (g), and in this embodiment, the threshold value α
(G) was set to 6 (g). After the integral calculation in step 124, when the first speed change value V1 is negative, step 1
When NO is determined in step 26, the process proceeds to step 120, and the first speed change value V1, the second speed change value V2, and the calculation elapsed time t are all cleared.

First speed change value V1 and second speed change value V2
When both are equal to or greater than zero, the process proceeds to step 130 in FIG. 4, and the magnitude of the elapsed arithmetic time t is compared with the threshold value t1. This threshold value t1 indicates that the impact of a hammer blow or the like is caused by the ECU.
A large deceleration G occurs when it is added near
This prevents the air bag device from operating, and is provided for distinguishing a low-speed collision and a medium-speed collision described later. FIG. 6 shows a waveform of the deceleration G at the time of hammer blow. The calculation time is long because the pulse width is short and the waveform is a vibration waveform. Ignition is prohibited for several ms.

In step 130 of FIG. 4, when the calculation elapsed time t, that is, the time after starting the integral calculation is larger than the threshold value t1, it is determined as NO, and the routine proceeds to step 146. In step 130, the calculated elapsed time t is the threshold value t1.
In the following cases, YES is determined and the process proceeds to step 132. In step 132, it is determined to be YES when t = t1, the process proceeds to step 134, and when the first speed change value V1 is smaller than the threshold value TH1 in step 134, it is NO.
Then, the process proceeds to step 146.

At step 134, the first speed change value V1
Is greater than or equal to the threshold value TH1, YES is determined, and the high-speed collision flag is set to 1 in step 136. In step 132, when t ≠ t1, that is, when t <t1, it is determined to be NO, the process proceeds to step 138, and the operation determination is not performed. In this embodiment, the threshold value t1
Was set to 6 ms.

With respect to the processing contents of steps 130 to 136 shown above, when the time from the start of the integral calculation does not reach 6 ms, the airbag device is not judged to operate, and the integral calculation is started. When the time reaches 6 ms, the operation is judged, and even if the deceleration G is generated by the hammer blow, the operation is not operated for 6 ms.

In step 132, when the calculated elapsed time t is smaller than the threshold value t1, the process proceeds to step 138, and the threshold value of the calculated elapsed time t is determined. That is, when the calculated elapsed time t is larger than the threshold value (xx + 1), step 1
When NO is determined in 38, the process returns in step 144. When the calculated elapsed time t is equal to or less than the threshold value (xx + 1), YES is determined in step 138, and the threshold value determination of the second speed change value V2 is performed in step 140.

When the second speed change value V2 is smaller than the threshold value TH2, NO is determined in step 140, and the process returns in step 144. When the second speed change value V2 is greater than or equal to the threshold value TH2, YES is determined in step 140, and subsequently, the first speed change value V is determined in step 142.
The first and second speed change values V2 are set to zero, and the process returns at step 144.

Steps 138 through 144 above
The processing contents up to are reset even if the second speed change value V2 reaches the threshold value TH2 when the calculation elapsed time t is less than 6 ms and the calculation elapsed time t is equal to or less than the threshold value (xx + 1). Is to do. As a case where the deceleration of full scale (-36 g) or more occurs in a short time, disconnection of the acceleration sensor 15 is considered.

Therefore, the elapsed time t is equal to the threshold value (xx +
1) In the following, when the second speed change value V2 reaches the threshold value TH2, it is considered that the deceleration G other than the collision of the vehicle has occurred due to the disconnection of the acceleration sensor 15, and the operation determination is not performed. . It should be noted that xx in step 138 means ignition time and is defined by the equation 1.

[0024]

Xx = TH2 / G (1) where TH2 is the threshold value of the second speed change value V2 and G is the vehicle deceleration at full scale.

At step 134, the first speed change value V1
Is greater than or equal to the threshold TH1, the high-speed collision flag is set to 1, the process proceeds to step 146, and YE is performed in step 146.
It is determined to be S, and the process proceeds to step 148. Step 1
At 48, when the second speed change value V2 is equal to or more than the threshold value TH2, YES is determined, and at step 150, the inflator is ignited.

NO in steps 130 and 134
If it is determined that the high-speed collision flag is zero, it is determined to be NO in step 146, and the process proceeds to step 152. In step 152, when the ratio between the first speed change value V1 and the second speed change value V2 is greater than or equal to a predetermined threshold value K, YE
It is determined to be S, and the irregular collision flag is set to 1 in step 154.

In the following step 156, the irregular collision flag is 1, so that it is determined to be YES and the routine proceeds to step 158, where the second speed change value V2 and the threshold value TH3 are compared. Here, the threshold TH3 is larger than the threshold TH2.
When the second speed change value V2 is equal to or greater than the threshold value TH3, YES is determined in step 158, and ignition is performed in subsequent step 160.

First speed change value V1 and second speed change value V2
When the ratio of the
Since it is determined to be O and the irregular collision flag is zero, it is determined to be NO in the following step 156, and the process proceeds to step 162 of FIG. Further, the second speed change value V2 is equal to the threshold value T
When it is smaller than H3, NO is determined in Step 158, and the routine proceeds to Step 162.

In the processing of steps 130 to 136 and 146 to 150 described above, the first speed change value V1 and the second speed change value V2 are the threshold values TH1 and TH2, respectively, when the elapsed time t of calculation is 6 ms. If it reaches, the inflator is started. In addition, the line from step 146 to step 152 is as follows when the first speed change value V1 does not reach the threshold value TH1 even if the operation elapsed time t reaches the predetermined threshold value t1.
It means increasing the threshold value of the operation determination.

Here, the waveforms of the deceleration G in the case of low speed (about 15 km / h) collision and in the case of medium speed (about 30 km / h) collision are shown in FIG. 7 and FIG. Indicates that the deceleration G rises more gently at the initial stage of the collision than in the medium-speed collision, so that the first speed change value V1 does not reach the threshold TH1 even after the elapse of the predetermined time threshold t1.
By providing the line from step 146 to step 152, the operation in the low speed collision is avoided, and the operation of the airbag device in the medium speed collision is enabled.

The processing of steps 152 to 160 is performed when the elapsed time t of calculation is 6 ms or more.
When the ratio between the first speed change value V1 and the second speed change value V2 is greater than or equal to the threshold value K, the threshold value of the second speed change value V2 is set to TH2.
In other words, the calculated elapsed time t is 6 ms or more, and the ratio of the second speed change value V2 to the first speed change value V1 is a predetermined threshold value K1.
When it is smaller, the threshold value of the second speed change value V2 is increased.

Here, as shown in FIG. 7, in the deceleration G waveform in a low-velocity collision, since the deceleration G rises gently, the ratio of the deceleration component is lower than that of the high deceleration component. When the ratio of the second speed change value V2 to the first speed change value V1 is smaller than the predetermined threshold value K for a predetermined time or more, the low speed collision is increased by increasing the threshold value of the second speed change value V2. Can be avoided.

When NO is determined in steps 148, 156 and 158 of FIG. 4, 1 is subtracted from the threshold value TH4 in step 162 of FIG. 5, and the first speed change value V1 and the threshold value TH4 are determined in step 164. Make a comparison of. When the first speed change value V1 is equal to or greater than the threshold value TH4, YES is determined in step 164 and the process proceeds to step 166. If the calculated elapsed time t is 120 ms or less in step 166, YES is determined, and step 168 is performed. Is ignited at.

In step 166, the calculated elapsed time t is 12
When it is larger than 0 ms, it is determined as NO and step 170
Then, in step 170, the first speed change value V1, the second speed change value V2, and the calculation elapsed time t are all cleared,
The process returns at step 172. When the first speed change value V1 is smaller than the threshold value TH4 in step 164, N
It is determined to be O, and the process returns at the following step 172.

The processing from step 162 to step 172 is to reset the first speed change value V1 when the calculated elapsed time t is 120 ms or more, even if the first speed change value V1 reaches the threshold value TH4. The purpose of this is to prevent operation when a voltage shift occurs.
That is, if an offset displacement occurs in the acceleration sensor 15, for example, if an offset voltage displacement occurs in the negative direction by 1 g, it cannot be distinguished from a deceleration input of 1 g. It may lead to judgment.

In order to avoid the operation of the acceleration sensor 15 due to the offset voltage shift, if the first speed change value V1 does not reach the threshold value TH4 even if the calculation is performed for a certain time or longer, it is determined that the collision does not occur, and the determination calculation is performed. Will be reset. In this embodiment, the threshold value TH4 is set to decrease by 1 with the elapsed time t of calculation. In addition, in the present embodiment, 10 at the time of irregular collision at 30 km / h.
In order to achieve 0% ignition, the calculation elapsed time t in that case is 1
Since it has reached 00 ms, the threshold is temporarily set to 120
ms.

According to the present embodiment, the time after the first speed change value V1 becomes positive, that is, the calculation elapsed time t, is obtained by the above operation.
Exceeds a predetermined threshold value of 120 ms, the first speed change value V1
When it reaches the threshold value TH4, it is considered that it is due to the offset voltage shift of the acceleration sensor 15, and the first speed change value V1, the second speed change value V2, and the calculation elapsed time t are all cleared without performing the operation determination. Accelerometer 1
The operation of the airbag device due to the offset voltage deviation can be prevented, and the quality of the airbag device can be improved.

[Brief description of drawings]

FIG. 1 is a structural diagram showing a configuration of a first embodiment according to the present invention.

FIG. 2 is a detailed block diagram of a control device.

FIG. 3 is a main flowchart showing a processing procedure of a CPU of a control device.

FIG. 4 is a main flowchart showing a processing procedure of a CPU of the control device.

FIG. 5 is a main flowchart showing a processing procedure of a CPU of the control device.

FIG. 6 is a waveform diagram of deceleration during hammer blow.

FIG. 7 is a waveform diagram of deceleration at a low speed (about 15 km / h) collision.

FIG. 8 is a waveform diagram of deceleration at a medium speed (about 30 km / h) collision.

[Explanation of symbols]

 4 Ignition device 9 Airbag control device 15 Acceleration sensor 31 Transistor G Vehicle deceleration V1 First speed change value V2 Second speed change value t Calculation elapsed time xx Ignition time TH1, TH4 First speed change value threshold TH2, TH3 (2) Threshold value of speed change value t1 Threshold value of operation elapsed time K Threshold value of ratio between first speed change value and second speed change value

Claims (1)

[Claims] 1. A deceleration of a vehicle is detected by an acceleration sensor, a speed change value obtained by integrating the deceleration is compared with a predetermined threshold value set in advance, and the speed change value reaches the predetermined threshold value. At the time, in an airbag control device that activates an inflator that ejects gas and inflates the airbag with the gas from the inflator, calculates a first velocity change value that is a time integral of a deviation of the deceleration from the first reference value. A first speed change value calculating means, a second speed change value calculating means for calculating a second speed change value which is a time integration of a deviation with respect to a second reference value larger than the first reference value, and the first speed A change means or a change means for activating the inflator when the second speed change value reaches the threshold value, and the time after the first speed change value becomes positive exceeds a predetermined time. Then, when the first speed change value reaches the threshold value, the activation control of the inflator is not performed.